Replaceable track belt assemblies of the type including an endless flexible belt with a plurality of track shoes mounted peripherally thereon are currently being used by the industry on pneumatic tires as is disclosed in U.S. Pat. No. 3,773,394 issued Nov. 20, 1973 to C. E. Grawey and U.S. Pat. No. 3,899,220 issued Aug. 12, 1975 to C. E. Grawey, et al, and which are assigned to the assignee of the present invention.
In these assemblies the shoes which are mounted on the belt are secured thereto by a plurality of bolts which are screw threadably received in metal keeper bars which are captive in the elastomeric belt. Thus, while these track belt assemblies provide increased traction for the vehicle, and improved flotation and protection of the pneumatic tire on which they are mounted, the heavy loads on the shoes impose large forces thereon and on the retaining bolts.
Because of the heavy loads on the shoes and retaining bolts, the internal threads will occasionally strip out of the keeper bars and field repair thereof has been found to be difficult. Accordingly, the anchoring of the shoes to the keeper bars was modified to eliminate threaded holes therein, and separately replaceable retaining blocks utilized at the lateral end of the shoes with threaded bores therein. With this arrangement, each keeper bar had plain bores or clearance holes at the lateral ends thereof and was entrapped between the shoe and the retaining block by the bolts passing therethrough so as to securely anchor the shoes to the belt.
While the last mentioned anchoring system has proven extremely effective in securing the lateral ends of the shoes to the retaining blocks overlyingly adjacent the sidewalls of the tire, it lacks rigid mounting of the shoes centrally therebetween. Moreover, with the advent of higher forces through the track belt assembly, larger vehicle tires, and greater shoe widths, there is an increased need for greater anchoring rigidity of the shoe across the full width thereof.